The invention relates to a latency monitoring point for a network to provide a latency measurement function that enables a measurement of latency in a packet network.
Conventional methods for measuring latency in a packet network range from crude methods such as ICMP Ping to more advanced measurement methods such as delay measurements using Carrier Ethernet tools like ITU-T Y.1731.
These conventional methods need an instance of the protocol to be supported on each side of the signal path which is monitored. Furthermore, the conventional methods also need access to a time source on the device in which the monitoring function and protocol is supported. Conventional methods provided for measurement of latency in the packet network do inject test traffic into the data path which is being measured, thus potentially adding to the latency of the data traffic which normally traverses the data path when a packet is ready to send and a test packet transmission is in progress.
U.S. Pat. No. 7,787,438 B2 describes a method of using two or more round trip measurements between a first and a second node in a network to estimate a delay parameter in traffic between a first and a second node. The method of U.S. Pat. No. 7,787,438 B2 applies the same principles as the methods described above such as ICMP PING or for instance Y.1731 in that a packet is inserted into the stream and an operation is performed at the receiving node. Therefore, this method also incurs a delay for other traffic. The passive monitoring described in this US patent requires two or more monitoring systems. The incurring of further delay into the data traffic can be critical in high frequency services such as high frequency trading HFT services. Further, the additional delay caused by the latency monitoring can become critical for real time applications, in particular when security is involved. Accordingly, it is an object to provide an apparatus and a method which enable an accurate latency monitoring in a packet network avoiding latency generation when monitoring the latency.